1. Field of the Invention
The present invention relates to battery charging technology and more particularly, to a slot-type induction charger, which uses an induction charging receiver in a narrow slot of a thin thickness power base to receive an induced electric current from a power-supplying coil module of the power base by means of electromagnetic induction for charging an electromagnetic device being attached thereto.
2. Description of the Related Art
Following fast development of electronic and multimedia information technologies, notebook computer, tablet computer, smart mobile phone, PDA and many other handheld electronic devices have been continuously developed and have appeared on the market. These mobile electronic products commonly have light, thin, short and small characteristics, and are convenient for carrying. Further, related application software has also been continuously created, enhancing hardware performance.
However, when using an electronic device for mobile application, the first problem to be solved is the supplying of power supply. A mobile handheld electronic device generally uses a rechargeable battery to provide the necessary working voltage. When power is low, the rechargeable battery can be recharged. For charging the rechargeable battery of a digital electronic product, a battery charger shall be used. However, it is not economic to purchase a respective mating battery charger when buying a new mobile electronic device. Further, it is inconvenient to carry and store many different mobile electronic devices and the related mating battery chargers.
In view of the aforesaid problems, some manufacturers created electromagnetic induction type power supply device or the so-called wireless battery charger for charging handheld electronic devices. This non-contact electromagnetic induction power supply devices bring great convenience to users. Briefly speaking, an electromagnetic induction power supplying method uses two induction coils to transmit electric energy. The theory of operation of the electromagnetic induction power supplying method is same as conventional coil transformers. A wireless battery charger can charge different electronic devices that have built therein a mating induction coil. Thus, a wireless battery charger can charge different electronic devices, eliminating the drawbacks of conventional power supply devices that cannot give mutual support, are not interchangeable and inconvenient for carrying.
Commercial induction type power supply devices or wireless battery chargers commonly use two coil modules. One coil module works as a power-supplying end for emitting electric current. The other coil module works as a power-receiving end for receiving the induced electric current from the power-supplying end. The power-supplying coil module and the power-receiving coil module commonly comprise a magnetic conductor and a coil wound round the magnetic conductor. The power-supplying coil module emits electric energy through an induction surface thereof. A coil module has a certain amount of inductance, and works with a capacitor to create resonance, thereby inducing an electric current. FIG. 9 illustrates induction charger according to the prior art. As illustrated, the induction charger includes two planar spiral coils A1 respectively arranged in a respective planar substrate A inside a respective electronic device. As the induced electric current is transmitted through top and bottom sides of the planar spiral coil A1 of the power-supplying end, the induced electric current cannot be completely received by the planar spiral coil A1 of the power-receiving end. During transmission of the induced electric current, the transmitted electric energy may be partially received by surrounding components, causing heat damage. Therefore, the planar substrates A must be made of a magnetic material to insulate electromagnetic waves.
Magnetic materials may have the characteristic of being reflective, absorptive or conductive relative to electromagnetic waves. The normal way to obtain a better power transmission efficiency is to attach a magnetic material of high reflectivity relative to electromagnetic waves to the non-induction surface of the planar spiral coil A1 of the power-supplying end and a magnetic material of high absorbability relative to electromagnetic waves to the non-conduction surface of the planar spiral coil A1 of the power-receiving end. This measure can obtain better conversion efficiency. However, it is expensive and not easy to make a magnetic material having a reflective or absorptive characteristic relative to electromagnetic waves. Further, the big induction surface area of the planar spiral coil A1 at the planar substrate A can obtain better induction power. However, because the planar spiral coil A1 is close to a circular shape, not convenient for installation in a compact handheld electronic device. In consequence, the application of conventional induction type power supply devices or wireless battery chargers is limited.